Power transmitting unit and power receiving unit with control data communication and methods for use therewith

ABSTRACT

Aspects of the subject disclosure may include, for example, a wireless power receiver configured to receive a wireless power signal from a power transmitting unit. A wireless radio unit is configured to communicate with the power transmitting unit. A controllable rectifier circuit is configured to rectify the wireless power signal. The controllable rectifier circuit can include a rectifier configured to generate a rectified voltage from the wireless power signal, based on switch control signals. A rectifier control circuit is configured to generate the switch control signals and to generate first control data that indicates a first rectifier duty cycle of the switch control signals. The wireless radio unit sends the first control data to the power transmitting unit. Other embodiments are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority under 35U.S.C. 119(e) to U.S. Provisional Application No. 62/255,080, entitled,“POWER TRANSMITTING UNIT AND POWER RECEIVING UNIT WITH CONTROL DATACOMMUNICATION AND METHODS FOR USE THEREWITH,” filed on Nov. 13, 2015,which is hereby incorporated herein by reference in its entirety andmade part of the present U.S. Utility Patent Application for allpurposes.

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120 as a continuation-in-part of U.S. Utility applicationSer. No. 14/319,357, entitled “POWER AMPLIFIER FOR WIRELESS POWERTRANSMISSION”, filed Jun. 30, 2014, which claims priority pursuant to 35U.S.C. §119(e) to U.S. Provisional Application No. 61/970,147, entitled“POWER AMPLIFIER FOR WIRELESS POWER TRANSMISSION”, filed Mar. 25, 2014,both of which are hereby incorporated herein by reference in theirentirety and made part of the present U.S. Utility Patent Applicationfor all purposes.

BACKGROUND TECHNICAL FIELD

Various embodiments relate generally to wireless communication systemsand also to wireless charging of devices.

DESCRIPTION OF RELATED ART

Communication systems are known to support wireless and wirelinecommunications between wireless and/or wireline communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, Bluetooth Low Energy (BLE), advanced mobile phone services(AMPS), digital AMPS, global system for mobile communications (GSM),code division multiple access (CDMA), local multi-point distributionsystems (LMDS), multi-channel-multi-point distribution systems (MMDS),and/or variations thereof.

The Alliance for Wireless Power (A4WP) has promulgated a baselinesystems specification for interoperability of loosely coupled wirelesspower transfer for portable, handheld electronic devices. Thisspecification supports a 6.78 MHz for power transfers and a 2.4 GHzoperating frequency for management data transfers. The Wireless PowerConsortium (WPC) has also promulgated standards used for wirelesscharging of mobile devices, notably the Qi low power specification.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram of an example wireless powerenvironment.

FIG. 2 is a graphical diagram of example circuitry for wireless powertransmission.

FIG. 3 is a schematic block diagram of an example plot of iload versusthe angle Φ.

FIG. 4 is a schematic block diagram of example circuitry for wirelesspower transmission.

FIG. 5 is a schematic block diagram of example circuitry for reactancecompensation.

FIG. 6 is a schematic block diagram of example circuitry for reactancecompensation monitoring.

FIG. 7 is a schematic block diagram of example circuitry supportingphase-based current measurement.

FIG. 8 is a schematic block diagram of example circuitry for wirelesspower transmission.

FIG. 9 is a schematic block diagram of example circuitry for wirelesspower transmission.

FIG. 10 is a schematic block diagram of example circuitry for wirelesspower transmission.

FIG. 11 is a schematic block diagram of example circuitry forsynchronous control of multiple power signal sources.

FIG. 12 is a schematic block diagram of example circuitry forsynchronous control of multiple power signal sources.

FIG. 13 is a schematic block diagram of example circuitry forsynchronous control of multiple power signal sources.

FIG. 14 is a schematic block diagram of example circuitry forsynchronous control of multiple power signal sources.

FIG. 15 is a schematic block diagram of an embodiment of a wirelesscommunication device.

FIG. 16 is a schematic block diagram of an embodiment of components of awireless charging system.

FIG. 17 is a schematic block diagram of example circuitry for wirelesspower transmission.

FIG. 18 is a flowchart representation of an embodiment of a method.

FIG. 19 is a flowchart representation of an embodiment of a method.

FIGS. 20-21 are schematic block diagrams of an embodiment of a rectifierimpedance model.

FIG. 22 presents graphical diagram illustrating embodiments of rectifiervoltages and currents.

DETAILED DESCRIPTION

FIG. 1 shows an example wireless power environment 100. The wirelesspower environment 100 includes a number of portable devices 102, 104 anda charging station (CS) 110 in this example, but the wireless powerenvironment may include any device. The techniques described belowregarding wireless power may be implemented in virtually any wirelesspower scenario. For example, the devices 102 receiving the wirelesspower may charge a battery, capacitor, or other energy storagesubsystem. Additionally or alternatively, the devices 102, 104 mayoperate directly on the power received from the CS 110.

The CS 110 may include power signal circuitry (PSC) 122 to supply apower signal to a transmit coil 132 able to transmit the power signalsto the portable devices 102. The CS 110 may include a power source 124to support generation of the transmitted power signal. The PSC 122 mayconvert a source signal from the power source 124 into a form that theantenna may transmit. For example, the power source may provide a directcurrent (DC) or alternating current (AC) signal. The PSC 122 may includepower circuitry 126 which may tune the basic signal from the powersource to a particular frequency or signal level for transmission overthe transmit coil 132 to the devices 102.

In various implementations, the CS 110 may include a transceiver 152 tosupport RF communication, one or more processors 154 to supportexecution of instructions, e.g., in the form of applications, and carryout general operation of the device. The CS 110 may include memory 156for execution support and storage of system instructions 168 andoperation parameters 162. In some implementations, the transceiverelements may receive status and/or control signals from the portabledevices 102. In some implementations, the control and/or status signalsmay be used by the CS 110 to adjust power signal parameters and/or otherwireless power provisional strategies. For example, the signals mayallow for detection of new devices within the power signal range,determination of when a device in range has completed charging, and/orother status or control determinations. For example, a device 102 may incommunication with the CS 110 over a wireless protocol, e.g. Bluetooth,Wi-Fi or other wireless protocol via transceiver 152. Additionally oralternatively, the CS may monitor internal parameters for statusdetermination. For example, the load of 132 may be monitored todetermine the presence/absence of devices within power signal range. Forexample, monitoring of internal parameters may be used to supportcharging of a device 104 which may not be in data communication with theCS 110. The communication device may include a user interface 136 toallow for user operation of the device.

For wireless power transmission, current may be supplied to a transmitcoil. In some cases, the current supplied to the transmit coil maydepend on the load of the transmit coil. For example, the current in aclass D power transmission circuit may be expressed as:

$\begin{matrix}{\frac{2 \cdot {VDC}}{\pi} \cdot \frac{1}{{Zload}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where Zload is the impedance of the transmit coil and VDC is a voltagesupplied by a voltage source.

In some cases, the current level in the transmit coil may be controlledby varying VDC. For example, the voltage source may be a buck-boostconverter, with a constant DC power supply. The buck-boost converter mayallow the adjustment of the current over a range. For example, thisrange may vary from 0-40V for class E power transmission circuits andvary from 0-80V for class D power transmission circuits. These examplevoltages may be supplied for systems operating at 1 A(root-mean-squared, rms) and for a load impedance of up to 36Ω.

In some implementations, the value of Zload may vary over time. Forexample, when receiving antennas or other objects move in to or out ofproximity of the transmit coil, the load of the transmit coil will vary.In some implementations, the voltage supplied by the voltage source maybe adjusted to keep the peak current flowing in the transmit coilconstant.

FIG. 2 shows example circuitry 200 for wireless power transmission,including a power signal source 210. In some implementations, the powersignal source 210 may provide a sinusoidal, other oscillating waveform,or other time varying waveform, current to a transmit coil 270. Thepower signal source may use the output of a voltage source 212 as a basesignal. In some implementations, the voltage source 212 may supply a DCvoltage. The power signal source 210, which may include two paths 211,241 having high-side and low side modulators 222, 232, 252, 262. Thehigh-side modulators 222, 252 are tied to the high-side output of thevoltage source 212. The low-side modulators 232, 262 may be coupled tothe low side of the voltage source and reference level 205, e.g. ground.In various implementations, the high-side and low side modulators 222,232, 252, 262 may be positive metal-oxide semiconductor (pMOS)transistors or negative metal-oxide semiconductor (nMOS) transistors.Additionally or alternatively, bipolar junction transistors (BJT) may beimplemented.

The two paths 211, 241 may receive a clock signal from the clock source204. The clock signal may be passed along the first path (FP) 211 to theFP control circuitry 214. The FP control circuitry 214 may control FPdrivers 224 and 234. For example, the FP control circuitry may controlthe amplification level of the drivers 224, 234 based on systemconditions. In some cases, the amplification level may be set to achievea determined on-off signal ratio for the FP modulators 222, 232. In someimplementations, the FP control circuitry may supply operationalvoltages to the FP drivers to serve as a power source. The FP controlcircuitry 214 may pass the clock signal to the FP drivers 224, 234. TheFP drivers 224, 234 may amplify the clock signal to drive the FPhigh-side 222 and low-side 232 modulators.

The FP modulators 222, 232 may produce an oscillating power signal bymodulating the output of the voltage source 212. For example, the FPhigh-side 222 and low-side 232 modulators may cooperatively produce a50% duty cycle square-wave signal through coordinated on-off switching.

The clock source 204 may also pass the clock signal along the secondpath (SP) 241. The SP may include a phase delay 242. The phase delay mayshift the phase of the clock signal on the SP by an angle, Φ, withrespect to the clock signal on the FP. The delayed clock signal isoutput coupled from the phase delay 242 to the SP control circuitry 244.The SP control circuitry 244 may control SP drivers 254, 264. The SPdrivers 254, 264 may amplify the clock signal to drive the SP high-side252 and low-side 262 modulators.

The SP modulators 252, 262 may produce an oscillating power signal bymodulating the output of the voltage source 212. For example, the SPhigh-side 252 and low-side 262 modulators may cooperatively produce a50% duty cycle square-wave signal through coordinated on-off switching.The oscillating signal produced by the SP modulators 252, 262 may beshifted with respect that produced by the FP modulators by the angle Φ.In some cases, the FP oscillating signal may be considered to have phaseΦ/2 and the SP oscillating signal may be considered to have phase −Φ/2.

The output of the FP 222, 232 and SP 252, 262 modulators may be passedthrough a filter 271 including inductors 272, 274 and parallel or seriescapacitive 276 elements. The filter 271 may act as a LC filter andestablish a center frequency, ω0, for the example circuitry 200. Theoutput of the filter may be passed to the antenna coil. In someimplementations ω0 may be expressed as:

$\begin{matrix}{{\omega \; 0} = \frac{1}{\sqrt{{Linv} \cdot {Cinv}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

where Linv is the inductance associated with the filter 271 and Cinv isthe capacitance associated with the filter 271. In the filter 271, thetwo input branches from the FP and the SP are passed through inductors272 and 274, which may have inductance values 2*Linv. In the examplecircuitry 200, the halves of the signal are exposed to 2*Linv beforebeing combined. This may have a similar effect to passing the combinedcurrent through an inductor of value Linv.

In some implementations the circuitry 200 may act as a current sourceand the peak amplitude current (iload) may not be dependent on the loadof the transmit coil 270. In some cases, combining the two signals fromthe FP and the SP may allow the iload to be controlled by adjusting theangle Φ. Adding two repeating signals where one signal constitutes aphase shift of the other results in a third signal of the same time withan amplitude that depends on the angle and a phase shift that depends onthe angle. For example, iload may be expressed as:

$\begin{matrix}{{iload} = {\frac{{2 \cdot \omega}\; {0 \cdot {Cinv} \cdot {Vin}}}{\pi}{\cos \left( \frac{\Phi}{2} \right)}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

where Vin is the voltage supplied by the voltage source 212.

FIG. 3 shows an example plot 300 of iload versus the angle Φ. In theexample plot 300, the value of iload is normalized using the largestvalue of iload to produce a unitless quantity versus the angle Φ. Thelargest value of iload may be controlled by setting the parameters ofthe circuitry 200. For example, Vin and/or Cinv may be adjusted toincrease or decrease the range on which iload can be varied.

In some cases, phase based modulation may allow for high-speed currentlevel changes within the transmit coil. High-frequency changes in thecurrent may be achieved. In some implementations, the voltage level usedin the circuitry 200 may be defined by the application of the circuitry200. For example, the transmit coil load may not contribute to selectionof the implemented voltage level. In some cases, a reduced voltage levelrange may allow for the use of more compact integrated or discretecomponents.

FIG. 4 shows example circuitry 400 for wireless power transmission. Insome implementations, a matching network 475 may be included in thefilter 471 between the power signal source 410. The power signal source410 may operate similarly to the power signal source 210 of FIG. 2, butmay further include feedback control circuitry 490. The feedback controlcircuitry 490 may be used to determine the phase angle Φ to set betweenthe FP 211 and the SP 241. Additionally or alternatively, the feedbackcontrol circuitry 490 may be used to control the matching network 475.The matching network may include variable elements, such as variablecapacitors, that may be adjusted. For example, the matching network mayinclude variable parallel capacitors 473, 477, and series capacitor 479.The capacitors 473, 477, 479 may have capacitances C2, C3, and C1,respectively. The variable elements of the matching network 475 may beused to compensate of for the variation in components in the filter 471.Variations may include process, voltage, and temperature variations. Thecapacitor 485 may include a variable capacitance. The capacitor 485 maybe used to compensate for the reactance of the antenna. The capacitor485 may be a variable capacitor with capacitance Ccomp. In someimplementations, the capacitor 485 may be controlled by the feedbackcontrol circuitry 490.

In an example implementation, the current ω0 and iload, the currentbeing input into the coil, for the circuitry 400 may be expressed as:

$\begin{matrix}{{\omega \; 0} = \frac{1}{\sqrt{{Linv} \cdot \left( {{C\; 3} + \frac{C\; {1 \cdot C}\; 2}{{C\; 1} + {C\; 2}}} \right)}}} & {{Equation}\mspace{14mu} 4} \\{{iload} = {\omega \; {0 \cdot \left( {{C\; 2} + {C\; 3} + \frac{C\; {2 \cdot C}\; 3}{C\; 1}} \right) \cdot \frac{2}{\pi} \cdot {Vin} \cdot {\cos \left( \frac{\Phi}{2} \right)}}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

In various implementations, the feedback control circuitry 490 mayoperate sensors 466, 468 to measure current and/or other parameters atmultiple locations on the circuitry 400. The feedback control circuitry490 may use the parameter measurement to adjust the angle Φ between thephases of the signals on the paths of the power signal source 410. Thefeedback control circuitry 490 may also control the matching network 475based on the measured parameters. Additionally or alternatively, thecapacitor 485 may be controlled by the feedback control circuitry basedon one or more of the measured parameters. In various implementations,the sensors 466, 468 may measure the phase of the current before andafter the matching network 475. As discussed below, the multiple pointphase measurement may allow for a low loss or lossless currentmeasurement.

In various implementations, the transconductance of the system, Ysys,and the equivalent inverter capacitor, Cv, of the matching network maybe expressed as two different functions of C1, C2, and C3. In somecases, by adjusting C2 and/or C3, Ysys may be modified while Cv is heldconstant. Additionally or alternatively, Cv may be modified while Ysysis held constant. In various implementations, Cv and Ysys may beexpressed as:

$\begin{matrix}{{Cv} = {{C\; 3} + \frac{C\; {1 \cdot C}\; 2}{{C\; 1} + {C\; 2}}}} & {{Equation}\mspace{14mu} 6} \\{{C\; 2} = {\left. {{C\; 2} + {C\; 3} + \frac{C\; {2 \cdot C}\; 3}{C\; 1}}\Rightarrow{Ysys} \right. = {\frac{iLd}{Vin} = {\frac{\pi}{2}{j \cdot \omega}\; {0 \cdot C}\; 2}}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

where iload is the load current. Further, Iinv the current input intothe matching network may be expressed as:

$\begin{matrix}{{linv} = {{iload} \cdot \left( {1 + \frac{C\; 1}{C\; 3} + {{j \cdot \omega}\; {0 \cdot \mspace{110mu} C}\; 2 {\left( {{{j \cdot \omega}\; {0 \cdot L}\; {coil}} + {RL} + {j \cdot {XL}} + \frac{1}{{j \cdot \omega}\; {0 \cdot {Ccomp}}}} \right)}}} \right)}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

where Lcoil is the inductance of the transmit coil, and j is the squareroot of −1. The expression RL+j*XL represents the reflected impedancefrom the power receiving unit.

FIG. 5 shows example logic 500 for reactance compensation. The logic 500may start by setting a determined angle, Φ0, between the signal paths(502). The determined angle Φ0 may be a default starting value. In somecases, the angle may be selected based at least in part on safetyconcerns. For example, the angle may be selected to keep heating in thetransmit coil below a certain level. The logic may set Ccomp such thatthe measured phase of the current before the matching network θinv andthe phase of the current at the input of the coil θcl are 90 degreesapart (504). The logic 500 may vary Cinv while holding Ysys constant(506). The logic 500 may vary Ysys to locate the point where iload hasthe minimum derivative with respect to Ccomp.

The logic 500 may vary Ysys while holding Cinv constant (508). The logic500 may vary Ysys to set the load current iload at a determined value.The determined value of iload may be determined by the application. Forexample, iLd may be selected based on the charging parameters of adevice. The logic 500 may monitor the reactance compensation of thesystem (510). For example, the logic 500 may implement the logic 600below to monitor the reactance compensation of the system.

FIG. 6 shows example logic 600 for reactance compensation monitoring.The logic 600 may monitor the angle between θinv and θcl (602). Forexample, the logic 600 may determine if the angle between θinv and θclhas drifted from a value of 90 degrees. The logic may determine if theangle between θinv and θcl has changed such that a compensation processmay be initiated (604). For example, the logic 600 may determine if theangle between θinv and θcl differs from 90 degrees more than adetermined threshold. Based on the determination, the circuit mayinitiate compensation (606) or continue monitoring the angle betweenθinv and θcl (602). For example, the logic 600 may implement the logic500 to perform reactance compensation. In some implementations, thelogic 600 may implement the logic 500 using the current angle betweenthe two paths as the determined angle Φ0.

In some implementations, a resistor may be placed in series with atransmit coil and a ground. The resistor may be used for an Rsensingcurrent measurement. In some cases, Rsensing current measurements may beassociated with losses within transmit coil system.

In some cases, the measurement of current within the transmit coil of awireless power system may be accomplished using the sensors or otherdetectors used in a phase measurement.

The phase measurement sensor may also be used to calibrate a matchingnetwork coupled to the transmit coil.

FIG. 7 shows example circuitry 700 supporting phase-based currentmeasurement. A power signal source 710 supplies a current signal to theinput of a matching network 775. The output of the matching network iscoupled to the transmit coil 770. Two phase sensors 766, 768 are placedat the input and output of the matching network. The current, i1, at theinput of the matching network is controlled by the signal supply 710.The current at the output of the matching network, i2 may be expressedin terms of i1, the phase angle between the measurement points, φ21,phase of the current at the input to the matching network, φ1.

To calculate the relationship between i1 and i2, parameter anglesbetween impedances y11 and y12 may be used. In various implementations,the relationship between the parameter angles and the currents may beexpressed as:

$\begin{matrix}{{{i\; 1} = {{\left( {{y\; 11} + {y\; 12}} \right)\phi \; 1} + {i\; 2}}},{{{where}\text{:}\mspace{14mu} y\; 11} = \frac{i\; 1\left( {{\phi \; 2} = 0} \right)}{\phi \; 1}},{{{and}\text{:}\mspace{14mu} y\; 12} = {\frac{i\; 1\left( {{\phi \; 1} = 0} \right)}{\phi 2}.}}} & {{Equation}\mspace{14mu} 9}\end{matrix}$

Ccomp, the capacitance used to compensate for the reactance of thetransmit coil 770, may be supplied by a second matching network 785.When the circuitry 700 is simplified such that Ccomp is brought into thematching network and resistive and Rsensing elements are removed, theimpedances simplify into purely capacitive contributions. The anglesbetween the parameters are then 90 degrees because they representimpedances that are purely imaginary. For the example circuitry 700, therelationship between currents i1 and i2 may be expressed as:

$\begin{matrix}{{i\; 2} = {i\; {1 \cdot \frac{\cos \; \left( {\phi \; 1} \right)}{\sin \; \left( {{\phi \; 1} - {\phi \; 21}} \right)}}}} & {{Equation}\mspace{14mu} 10}\end{matrix}$

FIG. 8 shows example circuitry 800 for wireless power transmission. Thecircuitry 800 includes a class D power signal supply 810. Phasedetectors 866, 868 may supply phase measurements of the current from theinput to the matching network 875 and the output of the matching network875. The phase detectors 866, 868 may provide the measurement of thephase to control circuitry 812. The control circuitry 812, may adjustthe output the power signal supply 810 in response to the phasemeasurements. The matching network 875 may act as a component within afilter 871. The control circuitry 812 may adjust the buck-boostconverter 814 to increase or decrease the power signal output of thecircuitry 800. The control circuitry 812 may also adjust the voltageoutput of the converter 814 to compensate for changes in the transmitcoil load. The control circuitry 812 may adjust the matching network 875and the compensation matching network 885 to execute the phase basedpower measurement. Additionally or alternatively, the control circuitry812 may adjust the matching network to compensate for the reactance ofthe transmit coil 870.

In various implementations, the example circuitry 400 may be used toimplement the phase based current measurement using sensors 466 and 468.The phase-based current measurement may be implemented with virtuallyany wireless power transmission systems that use a matching network anda transmit coil.

FIG. 9 shows example circuitry 900 for wireless power transmission. Theexample circuitry 900, comprises multiple power signal sources 910, suchas power transmission units, and multiple transmit coils 970. Thecircuitry 900 may further include filters 971 and matching networks 975.The circuitry may also include compensation networks 985 to compensatefor the reactances of the coils 970.

In various implementations, the power signal sources 910 may drive themultiple coils synchronously. The power signal sources 910 may use acommon oscillator signal and may drive their respective coils at varyingphases using the common oscillator signal to maintain a synchronousrelationship. The phases of the power signal sources may be selectedbased on the application of the circuitry 900. For example, the phaserelationships may be selected to maximize power transmitted. In anotherexample, the phase relationships may be selected to shape the fieldgenerated by the power signal sources. In some cases, the receiving coilof a charging device may not be parallel to the transmit coils 970. Thephases may be selected to attempt to align the field for optimaltransmission to the receiving coil. In another example, one or more ofthe power signal source 910 may be deactivated while one or more otherpower signal sources 910 continue transmitting to control the shapeand/or power output of the circuitry 900. In some implementations, thephase relationships of the power signal source 910 may be fixed based onfixed delays within the circuitry 900. In other implementations, thephase relationships between the power signal sources 910 may not befixed. For example, the phase relationships may be dynamically adjustedusing control circuitry.

FIG. 10 shows example circuitry 1000 for wireless power transmission.The example circuitry 1000, comprises multiple power signal sources1010, such as power transmission units, and a single coil 1070. Thecircuitry 1000 may further include filters 1071 and a matching network1075. The circuitry may also include a compensation network 1085 tocompensate for the reactance of the coil 1070.

In various implementations, the power signal sources 1010 may drive thecoil 1070 synchronously. Similar to the circuitry 900 above, the phaserelationships of the power signal source 1010 in the circuitry 1000 maybe determined based on the application of the circuitry 1000.

The use of multiple coils and/or multiple power signal sources may allowfor efficient increases in the power transmitted by the one or morecoils. Additionally or alternatively, the power usage of individualpower signal sources may be reduced for a given peak power. In somecases, reduced power consumption may increase safety, by reducing theheat dissipated, and may reduce the size and/or complexity of the powersignal sources. In various implementations, the numbers of power signalsource and transmit coils may be generalized to N power signal sourcesand M coils, where one or more power signal source is provided per coil.The N power signal sources may be drive synchronously. In someimplementations, the N power signal sources may be able to deliver Ntimes the power of a single power signal source for a given signalsource design. In various implementations, different power signal sourcetypes may be used. For example class D, class E, parallel sources, suchas those of circuitry 200, 400, and/or other power signal sources may beused.

FIG. 11 shows example circuitry 1100 for synchronous control of multiplepower signal sources. The example circuitry may include a bus 1105between the secondary power signal sources 1110 and a primary powersignal source 1109. An oscillator 1101 may provide a common clock signalto the power signal sources 1110, 1109. A control circuitry 1108 in theprimary power signal source 1109 may receive phase information, currentinformation, load information, and/or other information from thesecondary signal sources 1110 over the bus 1105. The control circuitry1108 may transmit control information over the bus 1105 to the secondarysignal sources 1110 to adjust their phase relationships. Additionally oralternatively, the control circuitry 1108 may activate and deactivatethe power signal sources 1110, 1109. For example, power signal sources1110, 1109 may be activated or deactivated depending on their respectiveloads. The power signal sources 1110, 1109 may include sensors tocollect phase information. For example, the power signal sources mayinclude phase sensors to collect phase information. In variousimplementations, the secondary power signal source may collect phaseinformation at the inputs of their respective coils. Additionally oralternatively, in implementations where multiple power signal sourcesdrive a single coil, the power signals sources 1110, 1109 may collectphase information at the input to the matching network of the coil. Invarious implementations, phase information may be collected at the inputof the match network of a coil and the input to the coil for the powersignal sources 1110, 1109. Collection of phase information at both theinput and output of one or more matching networks may allow for currentmeasurements in addition phase measurements. Current and phaseinformation may be sent to the control circuitry 1108.

In some implementations, the circuitry 1100 may include a communicationinterface 1199 that may allow communication with a receiving device. Forexample, the communication interface 1199 may communicate over Bluetoothor another wireless protocol with the receiving device. Thecommunication interface 1199 may receive application information fromthe receiving device. Application information may include receiving coilsize, orientation information (such as accelerometer measurements and/orother orientation information), power consumption information, currentdemands, requests for transmitted power level adjustments, indicationsof charging status, and/or other application information. Thecommunication interface 1199 may transmit the application information tothe control circuitry 1108.

In some implementations, the control circuitry 1108 may implementforeign object detection based on load. For example, one or more powersignal sources 1110, 1109 may be switched on or off based on a change inthe load of a transmit coil. For example, the one or more power signalsource associated with transmit coil may be switched of in response to achange in the load of the transmit coil when no information is receivedover the communication interface identifying the source of the change inthe load. This may protect foreign objects from being exposed totransmitted power signals. Additionally or alternatively, some coils mayremain active while others are switched off. The powering down of thecoils may be localized to those with load changes reducing potentialinterruption to device charging and/or other transmit processes.

FIG. 12 shows example circuitry 1200 for synchronous control of multiplepower signal sources. In the example circuitry 1200, the oscillator 1201may be combined with the primary power signal source 1209. The secondarypower signal sources 1210 may receive their common clock signals from asensor 1267 that recovers the clock signal from the output of theprimary power signal source 1209.

FIG. 13 shows example circuitry 1300 for synchronous control of multiplepower signal sources. In the example circuitry 1300, the controlcircuitry 1308 may be separated from the power signal sources 1310. Thecontrol circuitry 1308 may receive information from the power signalsources over the bus 1105 and may transmit control information to thepower signal sources 1310. The power signal sources 1310 need notinclude primary and/or secondary designations.

FIG. 14 shows example circuitry 1400 for synchronous control of multiplepower signal sources. In the example circuitry 1400, theprimary/secondary power signal sources 1410 may include controlcircuitry 1412. The designation of primary power signal source may bechanged during operation and/or design of the circuitry 1400.

While the foregoing description has focused on has sensing and controlwithin a power transmitting unit to improve power transfer andefficiency, in other examples, the power receiving unit and powertransmitting unit can, in addition or in the alternative, exchangecontrol data in order to cooperatively improve power transfer andefficiency. Such further examples are discussed in conjunction withFIGS. 15-19 that follow.

FIG. 15 is a schematic block diagram of an embodiment of a wirelesscommunication device. A wireless communication device 1500 is shown suchas a 2G, 3G, or 4G/LTE smartphone capable of making and receivingwireless phone calls, and transmitting and receiving data using 802.11a/b/g/n/ac/ad (“WiFi”), Bluetooth (BT), Near Field Communications (NFC),or any other type of wireless technology. In addition to making andreceiving phone calls and transceiving data, the wireless communicationdevice 1500 optionally runs any number or type of applications. Thewireless communication device 1500 may draw energy from numerousdifferent sources. As one example, the wireless communication device 100may draw energy from the battery 1501. Other sources of energy includeWireless Power Transfer (WPT) energy sources such as charging station110. In that respect, described further below are techniques forharvesting power from wireless signals.

The wireless communication device 1500 is shown as a smartphone in thisexample, but the functions and features described herein can likewise beimplemented in other host devices such as a laptop, tablet, cellphone, aperipheral host device such as a keyboard, a mouse, a printer, amicrophone, headset, headphones, speakers or other peripheral, a driverassistance module in a vehicle or other vehicle based device, anemergency transponder, a pager, a watch including a smart watch, asatellite television receiver, a stereo receiver, music player, homeappliance and/or any electronic host device that is compatible withwireless charging or other wireless power transfer.

In the embodiment shown, the wireless communication device 1500communicates with a network controller 1550, such as an enhanced Node B(eNB) or other base station. The network controller 1550 and wirelesscommunication device 1500 establish communication channels such as thecontrol channel 1552 and the data channel 1554, and exchange data. Thewireless communication device 1500 may be exposed to many other sourcesof wireless signals as well, e.g., from a charging station 110 or otherpower transmitting unit (PTU), and wireless signals may be harvested inconjunction with the WPT techniques described herein.

In the embodiment shown, the wireless communication device 1500 supportsone or more Subscriber Identity Modules (SIMs), such as the SIM1 1502and the SIM2 1504. Electrical and physical interfaces 1506 and 1508connect SIM1 1502 and SIM2 1504 to the rest of the user equipmenthardware, for example, through the system bus 1510.

The wireless communication device 1500 includes communication interfaces1512, system logic 1514, and a user interface 1518. The system logic1514 may include any combination of hardware, software, firmware, orother logic. The system logic 1514 may be implemented, for example, withone or more systems on a chip (SoC), application specific integratedcircuits (ASIC), one or more processors, discrete analog and digitalcircuits, and other circuitry. The system logic 1514 is part of theimplementation of any desired functionality in the wirelesscommunication device 1500.

The system logic 1514 may further facilitate, as examples, decoding andplaying music and video, e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAVdecoding and playback; running applications; accepting user inputs;saving and retrieving application data; establishing, maintaining, andterminating cellular phone calls or data connections for, as oneexample, Internet connectivity; establishing, maintaining, andterminating wireless network connections, Bluetooth connections, orother connections; and displaying relevant information on the userinterface 1518. The user interface 1518 and the inputs 1528 may includea graphical user interface (GUI), touch sensitive display, voice orfacial recognition inputs, buttons, switches, speakers and other userinterface elements. Additional examples of the inputs 1528 includemicrophones, video and still image cameras, temperature sensors,vibration sensors, rotation and orientation sensors, headset andmicrophone input/output jacks, Universal Serial Bus (USB) connectors,memory card slots, radiation sensors (e.g., IR sensors and/or othersensors), and other types of inputs.

The system logic 1514 may include one or more processors 1516 andmemories 1520. The memory 1520 stores, for example, control instructions1522 that the processor 1516 executes to carry out desired functionalityfor the wireless communication device 1500. The control parameters 1524provide and specify configuration and operating options for the controlinstructions 1522. The memory 1520 may also store any BT, WiFi, 3G, orother data 1526 that the wireless communication device 1500 will send,or has received, through the communication interfaces 1512. The wirelesscommunication device 1500 may include a power management unit integratedcircuit (PMUIC) 1534. In a complex device like a smartphone, the PMUIC1534 may be responsible for generating, e.g., thirty (30) differentpower supply rails 1536 for the circuitry in the wireless communicationdevice 1500.

In the communication interfaces 1512, Radio Frequency (RF) transmit (Tx)and receive (Rx) circuitry 1530 handles transmission and reception ofsignals through one or more antennas 1532. The communication interface1512 may include one or more transceivers. The transceivers may bewireless transceivers that include modulation/demodulation circuitry,digital to analog converters (DACs), shaping tables, analog to digitalconverters (ADCs), filters, waveform shapers, filters, pre-amplifiers,power amplifiers and/or other logic for transmitting and receivingthrough one or more antennas, or (for some devices) through a physical(e.g., wireline) medium.

As just one of many possible implementation examples, the wirelesscommunication device 1500 may include (e.g., for the communicationinterface 1512, system logic 1514, and other circuitry) a BCM59351charging circuit, BCM2091 EDGE/HSPA Multi-Mode, Multi-Band CellularTransceiver and a BCM59056 advanced power management unit (PMU),controlled by a BCM28150 HSPA+ system-on-a-chip (SoC) basebandsmartphone processer or a BCM25331 Athena™ baseband processor. Thesedevices or other similar system solutions may be extended as describedbelow to provide the additional functionality described below. Theseintegrated circuits, as well as other hardware and softwareimplementation options for the wireless communication device 1500, areavailable from Broadcom Corporation of Irvine Calif.

The charging station 110 or another power transmitting unit may generatea wireless power signal 1575. A controllable rectifier circuit 1560receives the wireless power signal via a wireless power receiver 1558.The output of the controllable rectifier circuit 1560 is the wirelesspower output signal 1562, Vrect, that can be used by charging circuit1564 to charge a battery 1501 of the wireless communication device 1500and/or to provide other system power.

In various embodiments, the controllable rectifier circuit 1560 includesa rectifier having a switching circuits configured to generate arectified voltage, Vrect, from the wireless power signal, based onswitch control signals that include a switch-on signal and a switch-offsignal for each switching circuit. A rectifier control circuit generatesthe switch control signals that generate a rectifier duty cycle thatdepends on the current loading conditions. In addition, the system logic1514 may exercise control over controllable rectifier circuit. Inparticular, one or more processors 1516 can execute control instructions1522 to change switching parameters that affect the switch timing andrectifier duty cycle of the controllable rectifier circuit 1560. Inaddition, the memory 1520 may also store nominal control parameters1566. The nominal control parameters 1566 may set or alter switchingtiming for the controllable rectifier circuit 1560 for pre-definedoperating scenarios of the wireless communication device 1500. Forexample, the switch timing and rectifier duty cycle may vary based onchanges in load and can differ in scenarios such as during startup ofthe wireless communication device 1500, during normal operation of thewireless communication device 1500, during high power or low powerconsumption of the wireless communication device 1500 (or any otherpower consumption mode as determined by comparison of current powerconsumption against one or more power thresholds), or during any otherpre-defined operating scenarios. In some implementations, the nominalcontrol parameters 1566 may be stored in a One Time Programmable (OTP)memory, with the nominal control parameters 1566 determined, e.g.,during a factory calibration process.

It should be noted that changes in the rectifier duty cycle can causevariations in the impedance reflected back to the power transmittercircuitry of the charging station 110. When a rectifier of thecontrollable rectifier circuit 1560 is “switched-on”, the load impedancemay appear as predominately resistive, while when the rectifier of thecontrollable rectifier circuit 1560 is “switched-off”, the loadimpedance may appear as predominately capacitive. These time-varyingimpedances are filtered by the receive and transmit coils into a moreslowly time varying quantity because the narrow bandwidth of these coilsoperates to filter the higher order harmonics produced by sharptransitions of this switching, while maintaining the fundamentalfrequency. Nevertheless, variations in rectifier duty cycle can lead tovariations in transmitter impedance that can cause further impedancemismatches that reduce power transfer and efficiency.

As previously discussed, the power receiving unit 1555 and chargingstation 110 exchange control data 1525 in order to cooperativelyestablish a charging session, and further to improve power transfer andefficiency. In the embodiment shown, the power receiving unit 1555wirelessly couples with the transceiver 152 of a PTU such as chargingstation 110, via a wireless radio unit included in transmit/receivecircuitry 1530 or a dedicated wireless radio unit included in powerreceiving unit 1555. The transmit/receive circuitry 1530 or a dedicatedwireless radio unit operate under control of the system logic 1514 or adedicated processor of PRU 1555 to establish the wireless connectionwith the charging station 110 via a connection establishment procedureand further to exchange control data 1525 with the charging station 110via the wireless connection.

In one example of operation, charging station 110 and PRU 1555 operatein accordance with a loosely coupled wireless power transferspecification such as the A4WP baseline system specification 1.0 (BSS1.0), however the Wireless Power Consortium (WPC) Qi low powerspecification or other wireless power transfer standards can likewise beemployed. In one example of operation, the wireless power signal 1575 isa 6.78 MHZ signal is sent from the charging station 110 and PRU 1555 totransfer energy to charge the wireless communication device inconjunction with a charging session. Control data 1525 is exchangedbetween the charging station 110 and PRU 1555 via a 2.4 GHz Bluetooth LEcompatible link to control the power transfer from the charging station110 to the PRU 1555. While described above in conjunction with a BLEwireless control channel between the charging station 110 and PRU 1555,other wireless control channels using other wireless standards and/orload modulation of the wireless power signal 1575 can likewise beemployed.

In various embodiments, the control data 1525 includes an indication ofthe current rectifier duty cycle that is sent to the charging station110 and can be used to adjust the transmit impedance to compensate, forexample, for the current loading conditions. In particular, changes inrectifier impedance caused by duty cycle variations can be estimatedbased on techniques that will be described in greater detail inconjunction with FIGS. 20-22 and used by the charging station 110 tocompensate.

In another example, the charging station 110 can transmit a desiredrectifier duty cycle to the PRU 1555 to improve power transfer and thecontrollable rectifier circuit 1560 can adjust its switch timing toachieve the rectifier duty cycle requested by the charging station 110.In other embodiments, charging data 1525 can be exchanged between thecharging station 110 and the PRU 1555 as part of an iterative procedureto adjust the rectifier duty cycle until power transfer is optimized, adesired level of impedance matching occurs and/or other performancegoals are reached.

Further embodiments describing the operation of the charging station 110and the power receiving unit 1555, including numerous optional functionsand features, are presented in conjunction with FIGS. 16-22 that follow.

FIG. 16 is a schematic block diagram 1600 of an embodiment of componentsof a wireless charging system. As just one example, the rectifiercircuit 1610 may harvest 6.78 MHz Alliance for Wireless Power (A4WP)power transmissions. The rectifier circuit 1610 facilitates efficiencyimprovements in receiving the transmitted energy and delivering it(e.g., as the rectified Direct Current (DC) voltage Vrect) to subsequentenergy consuming stages in the device, such as a battery chargingcircuit 1564 for the battery 1501.

Wireless power transmission suffers from efficiency losses at severalstages, e.g., from converting a power source into a radio frequency (RF)wireless power signal transmission, receiving the RF flux of thewireless power signal, and converting the RF flux into a usable DCvoltage in the receiving device. The wireless power receiver 1558employs magnetic resonance achieved through matching the inductance 1602and capacitance 1604 and 1606 to the transmitter system to obtain a highQ receiver that is very responsive to the fundamental frequency (e.g.,6.78 MHz) of the wireless power signal.

In that regard, the inductance 1602 may be a coil that receives the fluxof the wireless power signal. The inductance 1602 may be, for example,one or more turns of a conductor on a printed circuit board, or anothertype of antenna. The inductance 1602 produces an Alternating Current(AC) current and the capacitance 1604 and 1606 are tuned with respect tothe inductance 1602 to achieve the resonance that results in substantialresponsiveness to the wireless power signal. The wireless power receiver1558 provides the AC current into the rectifier circuit 1610,represented in FIG. 16 as a wireless power signal 1608 such as an ACcurrent signal represented by AC Positive (ACP)/AC Negative (ACN).

The rectifier circuit 1610 operates under control of the rectifiercontrol circuit 1620 to convert the AC current into the DC voltage,Vrect. In one implementation, the rectifier circuit 1610 and rectifiercontrol circuit 1620 are integrated into an integrated circuit chip,though in other implementations discrete components may be used. Therectifier circuit 1610 includes switching circuits (e.g., switchingcircuits 1612, 1614, 1616, and 1618) arranged to rectify the wirelesspower input signal to provide a wireless power output signal 1620. Theswitching circuits 1612, 1614, 1616, and 1618 may be Metal OxideSemiconductor FETs (MOSFETs), for example, or other types of transistorsor other types of switches.

FIG. 16 shows diodes associated with each of the switching circuits1612, 1614, 1616, and 1618 such as body diodes associated with FETimplementations of these switching circuits. The body diodes may haverelatively poor conductivity, such that even if the FETs turn on afterthe body diodes become conductive, the body diodes do not significantlyaffect the impedance tuning of the rectifier circuit 1610. In otherimplementations, switches without body diodes may be used. For example aFET switching structure including cascode connected transistors mayimplement the switches.

Rectifier control circuit 1620 controls the switching circuits 1612,1614, 1616, and 1618 using switch control signals 1638, 1640, 1642, and1644 to generate a wireless power output signal 1620, Vrect, as a fullwave rectified version of the wireless power input signal 1608 that isfiltered by capacitor 1650 into a substantially constant DC voltage—e.g.a DC voltage with acceptable variations or ripple. The switch controlsignals 1638, 1640, 1642, and 1644 include a switch-on signal and aswitch-off signal to individually control the ON and OFF states of eachof the switching circuits to provide efficient rectification.

The rectifier control circuit 1620 generates the switch control signals1638, 1640, 1642, and 1644 that generate a rectifier duty cycle thatdepends on the current load. The rectifier control circuit 1620 caninclude a processor or other circuitry that operates at high frequencies(above 1MHz) and uses of high bandwidth/low propagation delaycomparators to sense when to turn on and off the power FETs in theH-bridge. Wireless power systems are typically designed to operate at afixed (A4WP) or slowly varying (WPC) frequency. In this fashion, therectifier control circuit 1620 can control the rectifier duty cycle to anominal value that depends on the load conditions at the time.

In other examples, the system logic 1514, a processor or other circuitrymay be used to implement the rectifier control circuit 1620. Inparticular, one or more processors 1516 can execute control instructions1522 to change switching parameters that affect the switch timing andrectifier duty cycle of the controllable rectifier circuit 1560. Inaddition, the memory 1520 may also store nominal control parameters1566. The nominal control parameters 1566 may set or alter switchingtiming for the controllable rectifier circuit 1560 for pre-definedoperating scenarios of the wireless communication device 1500. Forexample, the switch timing and rectifier duty cycle may vary based onchanges in load and can differ in scenarios such as during startup ofthe wireless communication device 1500, during normal operation of thewireless communication device 1500, during high power or low powerconsumption of the wireless communication device 1500 (or any otherpower consumption mode as determined by comparison of current powerconsumption against one or more power thresholds), or during any otherpre-defined operating scenarios. In some implementations, the nominalcontrol parameters 1566 may be stored in a One Time Programmable (OTP)memory, with the nominal control parameters 1566 determined, e.g.,during a factory calibration process. Long term, as load power increasesand decreases, delay timing will change resulting in differing value ofrectifier duty cycles, but short term (over the span of several carrierclock cycles) the timing remains relatively constant.

In one example of operation, the rectifier control circuit 1620generates control data 1525 that indicates the current rectifier dutycycle. The transmit/receive circuitry 1530 or a dedicated wireless radiounit sends the control data 1525 to the charging station 110 for use bythe charging station 110 to adjust a transmit impedance.

In another operation, the transmit/receive circuitry 1530 or a dedicatedwireless radio unit receives control data 1525 from the charging station110 that is used by the rectifier control circuit 1620 to adjust theswitch control signals 1638, 1640, 1642, and 1644. For example thecontrol data 1525 received from the charging station 110 can includes anew rectifier duty cycle and the rectifier control circuit 1620 canadjust the switch control signals 1638, 1640, 1642, and 1644 to achievethe new rectifier duty cycle specified by the charging station. In thisfashion, the charging station can specify a specific rectifier dutycycle or recommended adjustments to the current rectifier duty cycle inorder to try to correct for an impedance mismatch or otherwise toimprove the power transfer of efficiency.

In other examples, the control data 1525 received from the chargingstation 110 includes transmitter performance data such as transmitpower, transmitter impedance mismatch or other transmitter performancedata that can be used by the rectifier control circuit 1620 to adjustthe switch control signals 1638, 1640, 1642, and 1644 in an attempt toimprove the transmitter performance. For example, the charging station110 can iteratively send control data 1525 that includes periodicupdates to the transmitter performance data and the rectifier controlcircuit 1620 can operate via a control loop or search algorithm based onthis feedback to iteratively adjust the switch control signals 1638,1640, 1642, and 1644 to arrive at the switch control signals 1638, 1640,1642 and/or a rectifier duty cycle that results in the best transmitterperformance under the current load conditions.

FIG. 17 shows example circuitry 1700 for wireless power transmission. Inparticular, the circuit includes many common elements described inconjunction with FIG. 8 that are referred to by common referencenumerals. The circuitry 1700 includes a class D power signal supply 810.Phase detectors 866, 868 may supply phase measurements of the currentfrom the input to the matching network 875 and the output of thematching network 875. The phase detectors 866, 868 may provide themeasurement of the phase to control circuitry 1712.

The control circuitry 1712 can include any of the functions associatedwith control circuitry 812 presented in conjunction with FIG. 8. Inparticular, control circuitry 1712 may adjust the output the powersignal supply 810 in response to the phase measurements. The matchingnetwork 875 may act as a component within a filter 871. The controlcircuitry 1712 may adjust the buck-boost converter 814 to increase ordecrease the power signal output of the circuitry 800. The controlcircuitry 1712 may also adjust the voltage output of the converter 814to compensate for changes in the transmit coil load. The controlcircuitry 1712 may adjust the matching network 875 and the compensationmatching network 885 to execute the phase based power measurement.Additionally or alternatively, the control circuitry 1712 may adjust thematching network to compensate for the reactance of the transmit coil870.

In addition, or in the alternative, the control circuitry 1712 receivescontrol data 1525 from the PRU 1555 that indicates the rectifier dutycycle and further may adjust the buck-boost converter 814 to increase ordecrease the power signal output of the circuitry 800, adjust thevoltage output of the converter 814, may adjust the matching network 875and/or may adjust the matching network to compensate for changes in theimpedance of the transmit coil 870 caused by current the rectifier dutycycle, adjust to reduce transmitter impedance mismatches, and/or tootherwise improve power transfer. In various embodiments, the controlcircuitry can determine an estimated or average rectifier impedancebased on the current rectifier duty cycle and implement adjustments tothe matching network to compensate. A specific methodology for modelingrectifier impedance as a function of rectifier duty-cycle is presentedin conjunction with FIGS. 20-22 that follow.

In addition or in the alternative, the control circuitry 1712 may alsouse phase detectors 866, 868 to indicate an amount of impedance mismatchthat can be used as transmitter performance data to generate controldata 1525 to be sent to the PRU 1555 in an attempt to improvetransmitter performance. The control circuitry 1712 may also monitortransmit power, power efficiency or other transmitter performance datathat can also be used to generate control data 1525 to be sent to thePRU 1555 to make in an attempt to improve transmitter performance.

In addition or in the alternative, the control circuitry 1712 may alsoinclude a look-up table, control algorithm or circuitry to generatecontrol data 1525 to indicate a specific desired rectifier duty cycle.The control circuitry 1712 can iteratively and/or periodically sendcontrol data 1525 that includes periodic updates to the transmitterperformance data that the PRU 1555 can use to iteratively adjust theswitch control signals 1638, 1640, 1642, and 1644 to arrive at theswitch control signals 1638, 1640, 1642 and/or a rectifier duty cyclethat results in the best transmitter performance under the current loadconditions.

While the charging station 110 and PRU 1555 may cooperate to improvetransmitter impedance mismatch, power transfer of efficiency, the mainburden of control can be assigned primarily to one device over theother. In the case where the control circuitry 1712 specifies arectifier duty cycle adjustment, the control circuitry 1712 can assumethe burden of waiting an appropriate time for the PRU 1555 to implementthe change, to re-monitor the transmitter performance and specify afurther adjustment as necessary in a search for improved performance.

In other cases, the control circuitry 1712 primarily serves as a sourceof periodic transmitter performance feedback that is used by the PRU1555 to adjust the rectifier duty cycle to conform with improvedtransmitter performance.

While particular control methodologies are outlined above, a wide rangeof other control techniques can be likewise be employed.

FIG. 18 is a flowchart representation 1800 of an embodiment of a method.In particular, a method is presented for use with one or more functionsand features described in conjunction with FIGS. 1-17. Step 1802includes generating, at a power transmitting unit, a wireless powersignal. Step 1804 includes receiving, at the power transmitting unit,first control data indicating a first rectifier duty cycle of a powerreceiving unit receiving the wireless power signal. Step 1806 includesadjusting a transmit impedance of the power transmitting unit inresponse to the first control data. In various embodiments, the methodcan include wirelessly associating the power receiving unit with thepower transmitting unit via a connection establishment procedure.

FIG. 19 is a flowchart representation 1900 of an embodiment of a method.In particular, a method is presented for use with one or more functionsand features described in conjunction with FIGS. 1-18. Step 1902includes receiving, at a power receiving unit, a wireless power signalfrom a power transmitting unit. Step 1904 includes generating switchcontrol signals via the power receiving unit. Step 1906 includesgenerating, via the power receiving unit, a rectified voltage from thewireless power signal, based on switch control signals. Step 1908includes generating first control data to indicate a first rectifierduty cycle of the switch control signals. Step 1910 includes sending thefirst control data to the power transmitting unit via a wireless radiounit.

In various embodiments, the power transmitting unit adjusts a transmitimpedance in response to the first control data. The method can furtherinclude receiving, via the wireless radio unit, second control data fromthe power transmitting unit; and adjusting the switch control signals inresponse to the second control data. For example, the second controldata can include a second rectifier duty cycle and the switch controlsignals can be adjusted to achieve the second rectifier duty cycle. Thesecond control data can include transmitter performance data such as anamount of transmitter impedance mismatch, transmitter power, a powerefficiency or other transmitter performance metric, and the switchcontrol signals can be adjusted, based on the transmitter performancedata.

In a further example the method include receiving, via the wirelessradio unit, second control data and updates to the second control datafrom the power transmitting unit and iteratively adjusting the switchcontrol signals in response to the second control data and the updatesof the second control data. The second control data can indicate anamount of transmitter impedance mismatch of the power transmitting unitand the switch control signals can be adjusted to control the amount oftransmitter impedance mismatch. The method can include wirelesslyassociating the power receiving unit with the power transmitting unitvia a connection establishment procedure of the wireless radio unit.

FIGS. 20-21 are schematic block diagrams of an embodiment of a rectifierimpedance model. As previously discussed, changes in the rectifier dutycycle can cause variations in the impedance reflected back to the powertransmitter circuitry of the charging station 110. In particular, therectifier impedance changes with the state of the rectifier. Aspreviously discussed, a rectifier control circuit generates switchcontrol signals to turn ON and OFF the switches of the rectifierhalf-bridge circuits based on voltage thresholds or other timing thancan be predetermined or adaptable based on operating conditions. Therectifier conducts current when switches are ON and the rectifier blockscurrent when switches are OFF. In the embodiment shown, the rectifierswitches 2002 and 2004 can consist of an FET in parallel with abody-diode inherent to CMOS device physics. The body-diode conducts whenthe voltage across diode exceeds a voltage threshold, Vth even when FETis OFF.

FIG. 20 presents a model 2000 of the rectifier impedance in a rectifierON state, where current is flowing through a half-bridge circuit. Inthis case, the rectifier switches 2002 and 2004 are modeled as aparallel R-C circuit with the resistance Rfet representing the ONresistance of the switch and the capacitance Cfet representing thecapacitance of the switch. FIG. 21 presents a model 2100 of therectifier impedance in a rectifier OFF state, where no current isflowing through a half-bridge circuit. In the case, the rectifierswitches 2002 and 2004 are modeled with the resistor removed.

In operation, the rectifier circuit toggles back and forth between theON and OFF states two times during each AC cycle of the wireless powersignal. When the rectifier is “switched-on”, the load impedance Zrect onmay appear as predominately resistive. When the rectifier is“switched-off”, the load impedance may appear as predominatelycapacitive. Even though the rectifier is toggling between two differentimpedances over time, this time-varying impedance is filtered by thereceive and transmit coils into a more slowly time varying quantitybecause the narrow bandwidth of these coils operates to filter thehigher order harmonics produced by sharp transitions of this switching.

In various embodiments, the overall average rectifier impedance,Zrect_(ave) can be estimated based on an arithmetic mean of the ON stateand OFF state impedances.

${Zrect}_{ave} = \frac{{{Zrect}_{on}*T_{on}} + {{Zrect}_{off}*T_{off}}}{T_{on} + T_{off}}$

where T_(on) is the time in the ON state, T_(off) is the time in the OFFstate, and where the full period of the wireless power signal, T, can berepresented by

T=T _(on) +T _(off)

And the rectifier duty cycle can be represented by:

Duty_Cycle=T _(on) /T

In terms of Duty Cycle:

Zrect_(ave) =Zrect_(on)*Duty_Cycle+Zrect_(off)*(1−Duty_Cycle)

Based on the equations for Zrect_(ave) above, it should be noted thatfor smaller rectifier duty cycles (less than 50%), the rectifierimpedance would become more capacitive, because the more capacitiveZrect_(off) term would be weighted more heavily. Conversely, for largerrectifier duty cycles (greater than 50%), the rectifier impedance wouldbecome more resistive, because the more resistive Zrect_(on) term wouldbe weighted more heavily.

Simulations presented later in conjunction with FIG. 22 support theseconclusions and validate that such an average rectifier impedance can beused in evaluating the effects of changing rectifier duty cycle on therectifier impedance, and the load impedance as seen by that the chargingstation. In this fashion, the effects of rectifier duty cycle on changesin the load impedance can be evaluated and/or compensated by thecharging station using any of the techniques previously described. Whilethe foregoing has described a particular rectifier impedance estimatebased on an arithmetic average of ON and OFF state rectifier impedances,other rectifier models, and other estimation and averaging techniquescould likewise be employed.

FIG. 22 presents graphical diagram illustrating embodiments of rectifiervoltages and currents. In particular, the diagrams 2200, 2210 and 2220represent simulated results for the AC voltage and AC current for threedifferent loads, and consequently, three different rectifier dutycycles. The simulation results correspond to a 6.78 MHz resonant 1.6 μHLcoil driven by a wireless power signal from a charging station at thesame frequency. The FETs of the rectifier are modeled by an ideal switchwith a 0.1Ω on resistance, a 300 pF capacitance, driven by switchingsignals that turn the switch on with a threshold of 100 mV and off witha threshold of −50 mV. The value of Vrect varies to differing values2204, 2214 and 2224 as shown. The C_Vrect is set at 8 μF, the and theload resistance R_load is set at 10Ω for diagram 2200, 100Ω for diagram2210 and 1 kΩ for diagram 2220.

In diagram 2200, the duty cycle is 80% and a 10.4 ns current leadingdelay is present between the AC current 2202 and the AC voltage 2204. Indiagram 2210, the duty cycle is 51% and a 23.5 ns current leading delayis present between the AC current 2212 and the AC voltage 2214. Indiagram 2220, the duty cycle is 20% and a 34 ns current leading delay ispresent between the AC current 2222 and the AC voltage 2224. In summary,the current to voltage (I-V) delay gets smaller with heavier loads aspredicted, due to the decreased dominance of the capacitive componentand increased dominance of the resistive component of the rectifierimpedance.

It should be noted that the forgoing simulation results are presented asmerely a demonstration of the effects of rectifier duty cycle onrectifier impedance. Actual wireless power receivers and rectifiercircuits could be implemented with different components values,different component types, at different frequencies, etc.

As may also be used herein, the term(s) “operably coupled to”, “coupledto”, and/or “coupling” includes direct coupling between items and/orindirect coupling between items via an intervening item (e.g., an itemincludes, but is not limited to, a component, an element, a circuit,and/or a module) where, for indirect coupling, the intervening item doesnot modify the information of a signal but may adjust its current level,voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “operable to” or “operably coupled to” indicates that an itemincludes one or more of power connections, input(s), output(s), etc., toperform, when activated, one or more its corresponding functions and mayfurther include inferred coupling to one or more other items. As maystill further be used herein, the term “associated with”, includesdirect and/or indirect coupling of separate items and/or one item beingembedded within another item.

As may also be used herein, the terms “processing module”, “module”,“processing circuit”, and/or “processing unit” (e.g., including variousmodules and/or circuitries such as may be operative, implemented, and/orfor encoding, for decoding, for baseband processing, etc.) may be asingle processing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may have anassociated memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of the processing module, module, processing circuit, and/orprocessing unit. Such a memory device may be a read-only memory (ROM),random access memory (RAM), volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

Various embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality. To the extentused, the flow diagram block boundaries and sequence could have beendefined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

A physical embodiment of an apparatus, an article of manufacture, amachine, and/or of a process that includes one or more embodiments mayinclude one or more of the aspects, features, concepts, examples, etc.described with herein. Further, from figure to figure, the embodimentsmay incorporate the same or similarly named functions, steps, modules,etc. that may use the same or different reference numbers and, as such,the functions, steps, modules, etc. may be the same or similarfunctions, steps, modules, etc. or different ones.

The term “module” is used in the description of the various. A moduleincludes a functional block that is implemented via hardware to performone or module functions such as the processing of one or more inputsignals to produce one or more output signals. The hardware thatimplements the module may itself operate in conjunction software, and/orfirmware. As used herein, a module may contain one or more sub-modulesthat themselves are modules.

While particular combinations of various options, methods, functions andfeatures have been expressly described herein, other combinations ofthese options, methods, functions and features are likewise possible.The various embodiments are not limited by the particular examplesdisclosed herein and expressly incorporates these other combinations.

What is claimed is:
 1. A power receiving unit comprising: a wirelesspower receiver configured to receive a wireless power signal from apower transmitting unit; a wireless radio unit configured to communicatewith the power transmitting unit; and a controllable rectifier circuitconfigured to rectify the wireless power signal, the controllablerectifier circuit comprising: a rectifier configured to generate arectified voltage from the wireless power signal, based on switchcontrol signals; and a rectifier control circuit configured to generatethe switch control signals and to generate first control data thatindicates a first rectifier duty cycle of the switch control signals;wherein the wireless radio unit sends the first control data to thepower transmitting unit.
 2. The power receiving unit of claim 1 whereinthe power transmitting unit adjusts a transmit impedance in response tothe first control data.
 3. The power receiving unit of claim 1 whereinthe wireless radio unit receives second control data from the powertransmitting unit; and wherein the rectifier control circuit adjusts theswitch control signals in response to the second control data.
 4. Thepower receiving unit of claim 3 wherein the second control data includesa second rectifier duty cycle and wherein the rectifier control circuitadjusts the switch control signals to achieve the second rectifier dutycycle.
 5. The power receiving unit of claim 3 wherein the second controldata includes transmitter performance data and wherein the rectifiercontrol circuit adjusts the switch control signals, based on thetransmitter performance data.
 6. The power receiving unit of claim 5wherein the transmitter performance data indicates an amount oftransmitter impedance mismatch of the power transmitting unit.
 7. Thepower receiving unit of claim 1 wherein the wireless radio unit receivessecond control data and updates to the second control data from thepower transmitting unit; and wherein the rectifier control circuititeratively adjusts the switch control signals in response to the secondcontrol data and the updates of the second control data.
 8. The powerreceiving unit of claim 7 wherein the second control data indicates anamount of transmitter impedance mismatch of the power transmitting unitand the rectifier control circuit iteratively adjusts the switch controlsignals to control the amount of transmitter impedance mismatch.
 9. Thepower receiving unit of claim 1 wherein the wireless radio unitassociates with the power transmitting unit via a connectionestablishment procedure.
 10. A method comprising: receiving, at a powerreceiving unit, a wireless power signal from a power transmitting unit;generating switch control signals via the power receiving unit;generating, via the power receiving unit, a rectified voltage from thewireless power signal, based on switch control signals; generating firstcontrol data to indicate a first rectifier duty cycle of the switchcontrol signals; and sending the first control data to the powertransmitting unit via a wireless radio unit.
 11. The method of claim 10wherein the power transmitting unit adjusts a transmit impedance inresponse to the first control data.
 12. The method of claim 10 furthercomprising: receiving, via the wireless radio unit, second control datafrom the power transmitting unit; and adjusting the switch controlsignals in response to the second control data.
 13. The method of claim12 wherein the second control data includes a second rectifier dutycycle and wherein the switch control signals are adjusted to achieve thesecond rectifier duty cycle.
 14. The method of claim 12 wherein thesecond control data includes transmitter performance data and whereinthe switch control signals are adjusted, based on the transmitterperformance data.
 15. The method of claim 14 wherein the transmitterperformance data indicates an amount of transmitter impedance mismatchof the power transmitting unit.
 16. The method of claim 10 receiving,via the wireless radio unit, second control data and updates to thesecond control data from the power transmitting unit; and iterativelyadjusting the switch control signals in response to the second controldata and the updates of the second control data.
 17. The method of claim16 wherein the second control data indicates an amount of transmitterimpedance mismatch of the power transmitting unit and the switch controlsignals are adjusted to control the amount of transmitter impedancemismatch.
 18. The method of claim 10 further comprising: wirelesslyassociating the power receiving unit with the power transmitting unitvia a connection establishment procedure of the wireless radio unit. 19.A method comprising: generating, at a power transmitting unit, awireless power signal; receiving, at the power transmitting unit, firstcontrol data indicating a first rectifier duty cycle of a powerreceiving unit receiving the wireless power signal; and adjusting atransmit impedance of the power transmitting unit in response to thefirst control data.
 20. The method of claim 19 further comprising:wirelessly associating the power receiving unit with the powertransmitting unit via a connection establishment procedure.